Why didn't this annual (from last year) die?

San Mateo, CA

I am growing bidens pilosa and I think it is supposed to be an annual. Last spring I sowed the seeds (bought online) and it grew well, flowering, attracting bee(s), and setting seeds which I collected. In the winter it withered away, I trimmed it but I didn't toss it. This spring, leaves came back and flowers too, but so far no bees came, and the plant does not grow tall.
What is going on? I am in the San Francisco bay area. I would like to know if I should toss this plant, or re-pot/fertilize if there's still hope for another season. I am growing it for the seeds.
Thanks in advance for any advice!

Thumbnail by gsbird
Ayrshire Scotland, United Kingdom

Bidens is classed in many areas as a TENDER Perennial, in some quarters it's classed as an annual, it can grow for several years if it's happy in the spot chosen, in other area's it is grown as a hanging basket plant and used as an annual.
I can only assume you have been lucky to keep it for a second year and being in your area where it can get quite cold from the ocean winds, you have done well to get the plant to flower for a second year. I would imagine that as you have allowed the plant to go make seeds to collect this has perhaps weakened the plant as forming seeds uses up a fare bit of energy, why it has not had the bees calling this year is a mystery to me unless there have been no bees about earlier on in the season, but it's not only bees that pollinate our plants crawling insects do this work as do other insects, all you can do is gather any seeds from this years flowering shoots and see if they will give you better plants that can attract more bees. Personally I think the bees have been in short supply rather that the plant being at fault as you said the plant did grow and form more flowers for a second year.

Also I would grow it as an annual and set new seeds every year to make sure the plants are not weak in any way as they are freshly grown from new seeds.

Hope this helps a bit but perhaps someone in your area will come in and correct my train of thoughts.
Best Regards. WeeNel.

San Mateo, CA

Thank you WeeNel for your reply. I learned a lot from your post!
It's quite possible the bees are not around as much as last year. As long as there is nothing "sterile" about the flowers, I'll wait and see what happens later in the season. Meanwhile, using seeds I collected last year, I've grown a new generation that's growing fast.
Thanks again for helping out a new gardener!
- gsbird

Prairieville, LA(Zone 9a)

Bidens pilosa has become naturalized in California


Ayrshire Scotland, United Kingdom

Your very welcome gsbird, I dont profess to know everything, in-fact anyone who thinks they do are rather silly, like you with gardening, we all learn something new as we go along that includes all the experienced ones also, that's what's so good about gardening, there is no ending, soon as you feel a job is done, another one shows it'self on the horizon and off we go again, be happy in your new found hobby and try not to worry about every plant being a great one, we all know there are lot's of other stuff like the weather, the soil, the type of seed condition we use and ofcource do we know the type is a plant we really, really want to grow can flourish in our area, jeeeees, it is a learning curve eh!!!!
Have a great gardening season and stay in touch when you require any other help re gardening.
Best regards. WeeNel.

Prairieville, LA(Zone 9a)

Agreed...wouldn't life be boring if we had all the answers? Grin

Ayrshire Scotland, United Kingdom

I do believe I'm very rarely bored so maybe that's why I really don't know everything about anything ha, ha, ha, Your a treat Moon.
Best Regards. WeeNel.

Prairieville, LA(Zone 9a)

We all have our moments Nel....and some of them are amusing...grin

Have a lovely evening

San Mateo, CA

Thanks for the link, Moon. That's interesting. I could have collected seeds for free instead of buying them from ebay, haha...

Prairieville, LA(Zone 9a)

You are very welcome. Hope this helps you save a bit of money in the future. Check the link below, it will show a plant's status on what is native, naturalized, invasive or endangered.


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